Research articles

Current strategies for fabricating quantum dots embedded within nanowires suffer from a number of shortcomings. Now, a versatile self-assembly approach is demonstrated for fabricating core–shell GaAs–AlGaAs nanowires with appealing optical properties.

The ultrafast dynamic phenomena associated with thin magnetic films irradiated by a laser pulse have been proposed to occur through a process involving spin transport. The observation that this is also the case when the films are covered by a non-magnetic capping layer provides compelling evidence in favour of this scenario.

The mechanical properties of a spider’s web are spatially mapped using Brillouin light scattering. This non-contact approach can probe the elastic properties of single fibres, intersection points and glue spots within the web, as well as measure how the elastic stiffness changes in supercontracted silk fibres.

Although molybdenum alloys — often used in turbines and fusion reactors — can be easily hardened, they suffer from low ductility and toughness. Now, a nanostructuring processing route that leads to a microstructure consisting of submicrometre grains with nanometric oxide particles uniformly distributed in the grain interior achieves high-strength molybdenum alloys with large tensile elongation at room temperature.

Microneedle arrays coated with a pH-sensitive releasable layer act as an intradermal delivery system for polyelectrolyte films containing bioactive molecules for DNA vaccination. The implanted films co-deliver DNA, transfection agents and adjuvants, promoting local transfection and generating immune responses that can be tuned from days to weeks.

The monitoring of cell survival and functionality following their in vivo transplantation remains a challenge in clinical cell therapy. Now, using magnetic resonance imaging techniques and microcapsules with pH-sensitive components, in vivo cell death and cell viability patterns can be assessed with high anatomical accuracy.

How the shape of jammed particle packings influences their mechanical response is unknown except for specific cases. An algorithm that mutates the shapes of packings of bonded identical spheres to optimize the packing’s mechanical performance, and the experimental testing of the optimized shapes through three-dimensional printing, are now reported.

Metallic and ceramic surfaces can be rendered hydrophobic through a combination of multiscale surface structures and polymeric modifiers, but the imparted hydrophobicity is not robust to harsh environments. It is now shown that the lanthanide oxide series—a class of ceramics—is intrinsically hydrophobic as a result of their unique electronic structure, even after exposure to high temperatures and abrasive wear.

The expansion of a material in one or more directions under increasing hydrostatic pressure is a phenomenon known as negative linear compressibility. The demonstration that zinc dicyanoaurate exhibits an unusually large negative linear compressibility opens up possibilities for designing other materials with comparable properties.

It is shown that by controlling the relaxation of graphene adhered on a biaxially pre-stretched polymer substrate, graphene films can be reversibly crumpled and unfolded to form tailored hierarchical structures with tunable wettability and transmittance, and that the crumpled graphene–polymer laminates can be used as actuators.

Controlling the charge and spin states of single molecular complexes at metal interfaces is a challenging task. Scanning tunnelling microscopy experiments now show that doping metal phthalocyanines with alkali ions is an effective way to achieve this.

A suitably engineered plasmonic metamaterial featuring topologically protected sharp phase variations close to a zero-reflection point of incident lightwaves has now been demonstrated. Exploiting the high sensitivity of the abrupt phase changes, and by using reversible hydrogenation of graphene and binding of streptavidin–biotin, the detection of individual biomolecules and an areal mass sensitivity of the order of fg mm⁻² is reported.

The design of open crystalline arrangements of colloidal particles with attractive patches has been hampered by the difficulty in exploring the full range of conceivable parameters both experimentally or with simulations. An analytical theory that explains the role of entropy in stabilizing open colloidal lattices and that predicts the conditions at which stable crystal structures of patchy particles form is now reported.

It has been suggested that the cytoplasm of living cells can be described as a porous elastic meshwork bathed in an interstitial fluid. Microindentation tests now show that intracellular water redistribution plays a fundamental role in cellular rheology and that at physiologically relevant timescales cellular responses to mechanical stresses are consistent with such a poroelastic model.

Glasses with extraordinary kinetic stability have been made in the laboratory by physical vapour deposition. A computational algorithm that mimics such a deposition process now reveals that deposition at the temperature at which the configurational entropy vanishes leads to ultrastable glasses that are truly amorphous, pack uniformly and have energies that are equivalent to those of equilibrium supercooled liquids.